1. Field of the Invention
The present invention relates to novel thermosetting compositions, thermal latent carboxyl compounds and methods of preparation thereof. More particularly, the present invention relates to novel thermosetting compositions having excellent chemical properties, physical properties and weathering resistance and exceptionally excellent storage stability and suitable for preparation of coating compositions, ink, adhesive and molded plastics, novel thermal latent carboxyl compounds utilized for the preparation of the thermosetting compositions and methods of effectively preparing the thermal latent carboxyl compounds.
2. Description of the Prior Art
It is generally known that thermosetting compositions can be prepared from compounds having carboxyl groups and compounds having reactive functional groups which can form chemical bonds with the carboxyl groups by heating, such as epoxy group, silanol group, alkoxysilane group, hydroxyl group, amino group, imino group, isocyanate group, blocked isocyanate group, cyclocarbonate group, vinyl ether group, vinyl thioether group, aminomethylol group, alkylated aminomethylol group, acetal group and ketal group. The thermosetting compositions give cured products having excellent chemical properties, physical properties and weathering resistance and are widely utilized in the field of coating compositions, ink, adhesive and molded plastics.
However, the reactivity between the carboxyl groups and the reactive functional groups is generally very high and compositions in which compounds having carboxyl groups and compounds having the reactive functional groups are mixed together have problems that the composition is often gelatinized during storage or, in other words, that potlife is short.
For the purpose of solving the problems, it was proposed that carboxyl group was blocked by converting it to tertiary-butyl ester and the free carboxyl group was regenerated by elimination of isobutene by heating (Laid-Open Japanese Patent Publication Heisei 1-104646). However, this method requires high temperature, such as 170.degree.-200.degree. C., for the heat decomposition of the tertiary-butyl ester and problems remain from tile point of view of material saving and energy saving.